稀土掺杂氟氧化物三维光子晶体的可控合成及上转换发光增强研究

Rare earth (RE) doped upconversion luminescence materials have attracted much interest in recent years due to their unique luminescent properties and potential applications. However, the weak point of upconversion luminescence materials is the low upconversion luminescence efficiency, the small absorption cross-section of RE ions and the concentration and thermal quenching, which limit their overall efficiency and practical application. This project intends to prepare a series of high quality RE doped oxyfluoride three dimensional photonic crystals with wet-chemistry method. The modification of upconversion and near-infrared downconversion luminescence by changing the photonic band gap and the size of the porous structure and the effect of concentration quenching and temperature quenching was further investigated. Finally, a variety of spectral characterization, such as steady-state excitation and emission spectra, power-dependent spectra, transient dynamic analysis, temperature-dependent emission spectra and dynamics, and internal quantum efficiency will be adopted to reveal the physical nature of the interaction of multiple excited state processes, such as excited state absorption, energy transfer, cross relaxation and phonon assistant. Moreover, the general law of upconversion luminescence enhancement by photonic crystal will be discussed with the results of theoretical analysis. This project will provide a stable and efficient RE doped upconversion material and provide theoretical guidance and experimental basis for the application of these materials in the field of upconversion solar cells, bioimaging and optoelectronics.

稀土掺杂上转换发光材料由于具有独特的发光特性和潜在的应用前景，近年来吸引了广泛的研究兴趣。然而，上转换纳米材料通常都有发光效率低（<1%）、稀土离子的吸收截面小、浓度猝灭和热猝灭的缺点，限制了其总体效率及其实际应用。本项目拟通过湿化学的方法制备一系列高质量的稀土掺杂氟氧化物反蛋白石光子晶体。通过改变光子带隙位置以及多孔结构的大小对上转换发光过程、近红外下转换过程进行调控，并进一步探索其对浓度猝灭和温度猝灭的影响。最后通过稳态激发和发射光谱，变功率光谱，动力学过程，变温光谱及动力学，深入揭示上转换发光中多种激发态过程（激发态吸收、能量传递、交叉弛豫、声子辅助等）相互作用的本质规律。并结合理论模拟的结果深入分析并总结光子晶体对上转换发光增强的普遍性规律。本项目将提供一类稳定的、高效的稀土掺杂上转换材料，并为这类材料在上转换太阳能电池、生物成像以及光电子领域提供面向实际应用的理论指导和实验依据。

掺杂纳米发光材料具有重要的应用前景，但在实际应用中还存在发光效率低等瓶颈问题。针对掺杂发光材料的发光性质与材料的尺寸、结构、形貌和掺杂依赖关系，本课题主要从稳态光谱到荧光动力学过程、从电子跃迁与晶格弛豫到能量传递、从上转换材料到其中的物理机制、从简单材料到复合型功能材料、从有机发光材料的合成到有机无机复合材料，开展对掺杂发光材料构筑路线、物理机制以及相关新型功能材料实现的研究：1）合成了NaYF4:Yb3+,Er3+@NaYF4:Yb3+,Nd3+@Cu2−xS核壳结构，系统研究了多波长808,980,1540nm激发下的上转换发光增强，分别对808,980,1540nm激发下的上转换增强倍数分别是6,12和5倍，提出了局域表面等离子共振和双光子效应协同作用增强机理，并把核壳结构的纳米粒子纳米压印在纸质基质上，通过不同红外光的辐射显示出不同的颜色，这一特性可以应用在防伪、加密和显示领域。2）合成了Cr3+钝化CsPbCl3:Cr3+,Mn2+的钙钛矿量子点（PQDs），研究了其光致发光的量子效率（PLQYs），应用于钙钛矿太阳能电池的光谱转换层，PSCs的能量转换效率（PCE）从20.81%增加到22.35%，相对提高了7.40%，提出了PLQYs提升的机理以及对钙钛矿太阳能电池能量转换效率提升的机制。3）设计并实现了钯催化的C-H键直接芳基化反应选择性可控地合成一系C2(5)-C2ʹ(5ʹ)位点连接的联二噁唑衍生物，并研究了噁唑的连接取向对其光物理性能的影响。